Seattle to Las Vegas

I am planning to drive to Vegas at the end of October.
I've done the coast road, Yosemite and Death valley before and Google map suggested a route through Salt lake city.
Visiting Bryce and Zion would be good.
Is there anything to see on the route form Seattle->Boise->Salt lake?
I assume most of Oregon is lakes and mountains but don't know a lot about Idaho - especially the southern bit.

Shoshone Falls

You would be close enough to make a detour to Twin Falls and the actual falls - Shoshone Falls - though these are more spectacular in spring than autumn. Then just a little up the canyon you can see the spot where Evil Kenevil (sp?) attempted to jump the canyon on his motor cycle... but failed!

Lifey who also loved the scene at the bridge over the river north of town